"Why do this to yourself" achievement won't unlock

Hi all,

My friend (WhatThe0x) and I have now played through the Reach LASO playlist twice (once with myself hosting, and once with him hosting). However he has not gotten the Achievement on either run-through.

We made sure his Playlist progress was at 12/12 before we finished the second playthrough, but he still never got the achievement. This is infuriating as a player, and we do not want to play a third time, especially without knowing that the achievement will actually work.

Can the dev team please fix the check for this achievement (check for playlist completion on game startup, or something similar) so that the Achievement can unlock for us and any other players who have completed the playlist but never got the Achievement?

If not, how can we make sure that we get the Achievement on a third playthrough?

Might be worth noting that I’m currently signed into a different microsoft account than what I play on. I play on the gamertag Raptor52152, and the friend who is having issues is on WhatThe0x